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OPA4171: buffer circuit

Charles Zhang1
Expert 3480 points

Part Number: OPA4171

Hi Team,

My customer uses OPA4171 as a buffer with single supply configuration(V- is connected to GND), they have observed a 0.4-V signal on OPA's output when V+ is OFF(no supply) and IN+ remains 2V(input signal has not cut off).

What might be the reason behind this observation? 

Besides, is it possible to damage the device if we give input signals before giving supply to OPA?  

Thanks.   

  • +1
    Guru 140200 points

    Hi Charles,

    the OPA4171 is partially biased by the 2V input voltage and the input current internally flowing via the input protection diodes to the supply pins. The 0.4V at the output is just the consequence of this scenario. See figure 40 of datasheet.

    Whether this can damage the OPA4171 depends on whether the input current is limited to below 10mA.

    Kai